Good cartridges around 500 usd?

The 2M Black is a logical upgrade. I own one and it's really a great moving magnet cartridge.

Do you have the ability to run moving coil or are you limited to moving magnet? 

I can go to mc

2M Black is my favorite current cartridge as well. At any price.

If you would like to upgrade from one cartridge to another then maybe you would like to hear something different from what you already have.

Put your Danish Ortofon against some serious Japanese MM cartridges such as AT-ML series from the 70s/80s (mid compliance), Grace F-9 series from the late 70s (high compliance), Victor X-1IIe (mid compliance) .. they are all under $500 or close. Terrific cartrisdges! 

Grado signature XTZ (MI) will kill it IMO 

High compliance AT20SLa Limited Editoon (with Nude Shibata) is the champ when it comes to $500 budget.  

The rest is depends on your tonearm and phono stage. 

grado sonata ref 2

I had an ATOC9III and it punched way above its weight. What turntable do you have. You should check out the specs on the tonearm and try to find something that is a good match from a compliance stand point. If it is off it can make a good cartridge sound bad, but if its a good match, a mediocre cartridge can sound really good.